1. Field of the Invention
This invention relates to the manufacture of woven fabrics with stretch in warp and/or weft direction. It specifically relates to fabrics and methods including a separated yarn system including an elastic core composite yarn system and a rigid base yarn system.
2. Summary of Related Art
Stretch woven fabrics or stretch wovens have been produced for many years. Fabric manufacturers generally know the importance of the right quality parameters to achieve fabrics acceptable to consumers. However, in these commercially available fabrics, the main body of the stretch fabric is formed by elastic composite yarn itself. Elastic yarn provides a double function: (1) the stretch yarn forms the base of the fabric to provide cover, aesthetic, and hand; and (2) the stretch yarn provides elasticity to provide stretch-recovery function. In many cases, the fabric appearance and performance are compromised by stretch function. Generally stretch fabrics have different appearance from rigid ones that do not include elastic yarns. Due to the inclusion of elastic yarn, many textile processes are difficult to conduct, such as indigo yarn dye for denim and package yarn dye for shirts. Also, textile production efficiency is reduced during processing elastic yarn. In most cases, extra contractive force exists within fabrics, resulting in poor fabric dimension stability. In order to provide such an elastic containing fabric with dimensional stability, heatsetting is a necessary process to control fabric shrinkage.
For stretch fabric, most elastic or elastomeric yarns are used in combination with relatively inelastic fibers, such as polyester, cotton, nylon, rayon or wool. However, for the purposes of this specification, such relatively inelastic fibers will be termed “hard” fibers.
Conventional composite yarns including spun cotton and elastomer fiber are typically dyed as packages before use in weaving, but there are disadvantages. Specifically, the elastomer core yarn will retract at the hot-water temperatures used in package dyeing. In addition, the composite yarn on the package will compress and become very tight, thereby impeding the flow of dyestuffs into the interior of the yarn package. This can often result in yarn with different color shades and stretch levels, depending on the yarn's diametrical position in the dyed package. Small packages are sometimes used for dyeing core-spun composite yarns to reduce the problem. However, small-package dyeing is relatively expensive because of extra packaging and handling requirements.
Although common industry practices are highlighted above, additional references are described hereinbelow to demonstrate attempts to improve weaving processes and/or products. For example, U.S. Pat. No. 3,169,558 discloses a woven fabric with bare spandex in one direction and hard yarns in the other direction. However, the bare spandex must be draw twisted in a separate process, and spandex could be exposed on fabric surface.
Great Britain Patent GB 15123273 discloses a warp-stretch woven fabric and process where pairs of warp yarns, each pair having a bare elastomer fibers and a secondary hard yarn, are passed in parallel and at different tensions through the same heald eyelet and dent. However, the spandex is also visible on the face and back of fabric.
Japanese published Application 2002-013045 discloses a process used to manufacture a warp-stretch woven fabric using both composite and hard yarns in the warp. The composite yarn comprises polyurethane yarn wrapped with a synthetic multifilament hard yarn and then coated with size material. The construction of the composite is that of the composite yarns represented in FIG. 3, before coating with size material. The composite yarn is used in the warp in various proportions to a separate synthetic multifilament hard yarn in order to achieve the desired properties of stretch in the warp direction. This composite yarn and method were developed to manufacture warp-stretch fabrics, and to avoid difficulties in the weaving of weft-stretch fabrics. However, the elastic yarns have the same size as hard yarn and exposed on the fabric surface.
U.S. Pat. No. 6,659,139 describes a way to reduce grin-through of bare elastomer in warp direction of twill fabric. However, the elastomers are used in bare form and elastomer slippage occurs after the garment is washed. The workable fabric structure window is narrow and the weaving efficiency is low.
Therefore, there is a need to produce stretch wovens, which are low shrinkage, easy process, friendly garment making.